Yes my understanding is that gen4 springs are interchangeable between all Gen4 struts.
Eg our 2.5i is on Koni sport struts, Rallitek springs and these springs would fit kyb or Bilstein etc struts.
Kings make super low (or they used to) springs that adequately lower the front of a 2.5i.
Bee R springs were also available in Down and Full Down versions.
Some Japanese companies eg PROVA made specific non GT/H6 spring sets, if I remember correctly.
As per my original comment, if your stock rear springs are already sagged, maybe just run front lowering springs before committing to rear lowering springs?
Try a site specific search?
https://www.google.com.au/search?q=site ... s-wiz-serpBear in mind some struts are designed with lowering as part of the design brief.
I’m not sure if this applies to stock KYB’s, if I was lowering these I’d probably upgrade the strut bump stops to shorter, harder type.
Be sure to reset all lateral arm bolts at static height after the initial lowering and again once the suspension has fully settled, to prevent undue torsional load on the captive bushes.
I’d be very tempted to also install a Whiteline or Hardrace etc roll centre adjustment kit, lowered or not.